seejpeg v1.4.3 ------------------------------------------------------------------ Copyright (C) 1993, 1994 Evan Harris Permission is granted to freely redistribute and modify this code, providing the author(s) get credit for having written it. ------------------------------------------------------------------ seejpeg is another JPEG viewer which utilizes svgalib and contains limited GIF, PPM and TARGA viewing support. The most useful feature of seejpeg is that it automatically decides on the "best" video mode to use based on the image being displayed and the video card being used. To aid it, various hints may be given as program options. In the worst case, it may be overridden. Video modes supported are limited to 1280x1024, 1024x768, 800x600, 640x480 and 320x200 in 256, 32K or 16M colours (assuming the video card, and svgalib, supports these modes). Logical screen sizes are only limited by the size of video memory. In normal mode, if the image is larger than the screen size the arrow keys may be used to scroll around that part of the image which could be loaded into video memory. Pressing any other key exits the program. ------------------------------------------------------------------ Program options =============== -q QUANTIZE PICTURE (256 colour mode) (JPEG only) This option forces the image to be quantized into a colour map with 256 entries, and subsequently seejpeg uses a 256 colour mode. If this option is not given seejpeg will not use a 256 colour mode unless the TESTMODE is not available (see below) in which case it will implicitly set -q. The default quantization to use is two pass quantization - this is memory intensive and may cause the machine to page if the image is large or memory is small. This should be the only occasion in which seejpeg causes a machine to page. -1 ONE PASS QUANTIZATION (-q implicit) (JPEG only) As -q, except that it uses one pass quantization. This does not cause a machine to page, but the results are worse, unless the image is greyscale. -g FORCE GREYSCALE MODE (-1 implicit) (JPEG only) Display the image in greyscale. This is not necessary for an image compressed using the greyscale option on cjpeg as this mode will be set automatically. It can be used for images compressed without the greyscale flag, or for displaying colour images in greyscale. -v VERBOSE Display the video modes being used, the program version number and lots of other stuff. Without this option, seejpeg operates silently. -w ONLY USE WIDTH TO DETERMINE VIDEO MODE By default, the video mode chosen is the smallest one possible which is not smaller than the image. This may not be desirable for long, thin images. It may be preferable to choose the video mode based on the width only, rather than the width and height, in which case this option should be used. -f F SET FUZZ FACTOR TO DETERMINE VIDEO MODE A video mode is selected if it is larger than the image. Using this option allows a video mode to be selected if it is larger than (or equal to) F * image_width and F * image_height. Currently, F must be in the range [0.5,1.0]. This option may be used in conjunction with -w to only use the image width. -F S FORCE THE USE OF THE GIVEN VIDEO MODE To completely override the video mode selection routines a video mode string (e.g. G640x480x32K) may be given instead. If this is a 256 colour mode, quantization (-q) is automatically selected. -dx DOUBLE THE SIZE OF THE IMAGE IN THE X DIRECTION -s T SHOW THE IMAGES IN A SLIDESHOW Each image is shown for T seconds. The images cannot be scrolled when being showed in a slideshow. The slideshow cannot be stopped or paused, except by the interrupt character (e.g. ^C). -C CYCLE THROUGH ALL IMAGES The program does not exit after showing all the images, instead it returns to the first image and shows them all again. Normally this can be stopped by pressing the Q key, at which point it will continue to show all images in the cycle and then stop. When showing the images in a slideshow this option will cause the slideshow to run forever (until interrupted by, e.g., ^C). In addition to colour and greyscale JPEG formats, GIF, PPM and TARGA image formats are supported to a limited degree. If the image is in GIF, PPM or TARGA format the -q, -1 and -g options are inoperative and, as a result, some video modes are not available for selection using -F. Unfortunately, due to a limitation in libjpeg, the GIF support has to perform its own colour map construction so it can use 256 colour modes. This may cause problems, although I haven't seen any yet. GIF support currently only uses 256 colour modes, however changing this should be easy, if the demand is there for it. GIF support has had limited testing. PPM support is barely tested. It uses 16M or 32K modes for colour images, and 256 modes for greyscale images. TARGA support is completely untested as I've never seen or generated a TARGA image. The -targa option of cjpeg is not included in seejpeg, let me know if something like it is required. ------------------------------------------------------------------ Compiling ========= This program requires version 0.91 or higher of svgalib. This is changed from previous versions because we now call vga_init() which gives up supervisor rights really quickly. The following symbols can be defined in the Makefile: PIX_ALIGN The constraints on the logical line length for different video cards are different. Some video cards (like my CLGD5426) want the logical line length to be a multiple of 8 pixels, while others don't look good unless it is a multiple of 64 pixels (such as some (all?) Mach32 cards). This value also affects the horizontal scrolling, so use the smallest you can get away with. The default value is now 64 pixels. Hopefully this produces good results for everybody. Other values that may be worth trying would be 8, 16 and 32. I recommend using the lowest value that produces a good display. NO_32K_CASCADE If the best mode is available in 16M and 32K modes and the complete image doesn't fit in memory using the 16M mode, the 16M mode is discarded and 32K mode used instead. If you define this option this action does not happen. The only time I can think of this option being useful is if a video card supports 16M modes but not 32K modes. TESTMODE This video mode is tested for - If the video card supports it, we assume that hicolor or truecolor (32K or 16M) modes are available. If the video card doesn't support it, we assume that only 256 colour modes are supported. If this is not set in the Makefile, it is assumed to be G640x480x32K. If there is a video card which supports hicolor or truecolor but not this mode, let me know of a better default to test for and I'll change it in the next release. BUG_WORKAROUND Some versions of svgalib with some video cards can scramble the video mode when multiple files or slideshows are shown. This appears to be avoided somewhat if the text video mode is set between each picture. This is what the workaround does. This may not be needed for some versions of svgalib or some video cards. It is for my CLGD5426 based card with svgalib 1.06. This option is defined by default in the makefile. Unless you change one of these options, or the default binary location, changing the Makefile should no longer be necessary. You now can build a version of seejpeg which uses libgr-1.3. This shared library is NOT included with seejpeg. It is available on sunsite in /pub/Linux/libs, amongst others. The seejpeg makefile assumes that the the installation is as per the README in libgr-1.3. If this is not the case, the definition of GRHEADERS may have to be changed in the makefile. ------------------------------------------------------------------ Acknowledgements ================ The following people have contributed to the development of seejpeg. Thanks everyone. Harm Hanemaayer <hhanemaa@cs.ruu.nl> ongoing svgalib development, putting up with lots of silly questions, providing lots of useful information, and a makefile bug report <wolter@wppc9.oz.au> Jean-Francois Cordeau <cordeauj@jsp.umontreal.ca> Peter Mutsaers <muts@compi.hobby.nl> <ahughes@muddcs.cs.hmc.edu> makefile bug report in 1.0 Jeff Grills <jefftep@cs.utexas.edu> colour lookup (256 colour mode) bug report in 1.2 Michael Weller <eowmob@exp-math.uni-essen.de> PIX_ALIGN patches against 1.1, prompting to add multiple images and the slideshow Nils Rennebarth <nils@exp-math.uni-essen.de> described how to compile with libgr-1.3 cleanly ------------------------------------------------------------------ Feedback ======== The current version was compiled and tested with svgalib version 1.06 and a 1MB CLGD5426 based video card. There are no known bugs with this configuration (in seejpeg, that is 8-). If you find a bug with any configuration please report it, including all the information displayed using the "-v" option. As of version 1.2, I have considered seejpeg "finished". Future releases will primarily be bug fixes, although new features may be added as well (as they were in 1.4). Please send any feedback, especially bug reports, to: Evan Harris (evan@cs.mu.oz.au)